1LDE000115 Transformers for converter applications 230413.indd

Transformers for variable speed drive applicationsTransforming electricity into value

Converter transformers and reactors

2 Converter transformers and reactors Converter transformers and reactors 3

Variable speed drive systemsReliability and quality

Variable speed drivesConverters are used to control the speed of rotation and

the torque of electric motors in many industrial applications.

Typically these are pumps, ventilators, compressors, belt

conveyors, rolling mills, paper machines and an innumerable

amount of different machines employed in manufacturing

and other industries. Converters are also operating in power

generation and in transportation systems, like ships or railway.

Electric motors consume about 65 % of all electricity used

throughout industry. Less than 10 % of those motors are

presently fitted with variable speed drives, which allow for

significant energy savings. In many cases savings of 50 %

or more have been demonstrated. Imagine the energy savings

if more motors were controlled by a variable speed drive.

The use of variable speed drives employs more sophisticated

methods to allow better control of industrial processes and

ensures higher quality and reliability.

Transformers for drive systemsThe transformer is the link between the supplying electrical grid

and the converter. It is a major component in the transformer-

converter-motor chain.

Different converters require different transformer confi gurations.

In many cases a multitude of secondary windings, connected

with different phase angles is required and special technical

solutions are needed due to the presence of harmonics and

voltage transients generated by the converter.

Thinking as a system, not as single componentsDrive applications are subject to high technical demand. All

components in the chain have to be harmonized. It is therefore

essential to handle the application as a combined system and

not as a set of single components.

Additionally, environmental and effi ciency aspects are getting

more and more important and need to be considered and

integrated.

ABB recognizes these specific requirements and, thanks to

its highest technical and personnel competence, is able to

offer optimized solutions, tailored for different application

segments. Continuous high investments in R&D enable ABB

to use the full scope of technologies and ensure high reliability

for products and systems.

Variable speed drives are everywhere: you can find them on board of a dredger, controlling the motors of a dam, in power plants or in mines.


Transformer portfolio for variable speed drive applicationsABB´s comprehensive experience

A pioneer in converter transformersABB is a pioneer in designing converter transformers and has

a long and proven track record in a broad range of state-of-

the-art technologies to ensure a constant stream of benefits

for customers. ABB converter transformers have accumulated

millions of operating hours worldwide.

Standardized and tailor-made solutionsCharacterized by their modular design, ABB converter trans-

formers and reactors provide a competitive edge in the key

operating areas of size, weight and reliability for almost any

requirement. Support is given by our best experts from our

Centers of Excellence for converter transformers. Transfor-

mers are built to match the requirements of any drive, from

any manufacturer.

Converter transformer portfolioWe offer liquid-immersed and dry-type transformers for low

voltage (LV, up to 1.1 kV), medium voltage (MV, up to 36 kV)

and high voltage (HV, >36 kV) applications.

Primary Secondary Liquid-immersed Dry-typevoltage voltage (kVA) (kVA)

LV LV 200 - 10’000 20 - 10’000

MV LV 200 - 10’000 100 - 10’000

MV MV 500 - 100’000 100 - 40’000

HV MV 1’000 - 100’000 on request

The transformers can have natural cooling, forced air cooling

or forced water cooling.

Reactors for drive applicationsA broad range of dry-type and liquid-immersed, iron-core

or air-core reactors for use in power converters or in drive

systems are available. Such components are used, for ex-

ample, in filters or as DC-link chokes.

Global experience - local solutionsABB is the world’s leading supplier of converter transformers.

Building on a worldwide presence with a dozen plants and

30 transformer service centers, we are close to you and able

to supply in different regions from local factories and to comply

more easily with local requirements, while still using a common

global design. With its global network of strong local resources,

ABB supports all players in the market with the expertise they

need for their projects.

ReliabilityABB converter transformers provide highest reliability, for

a safe and undisturbed operation of your drive installation.

Transformers are utilized in some of the harshest indoor

and outdoor environments imaginable. All transformers are

manufactured to the most stringent quality control standards

in order to guarantee the full reliability of the product.

Ecology and economyIt is ABB’s policy to provide customers with sustainable solu-

tions, optimized for both, the economical and the ecological

aspects. Solutions with low transformer losses and minimum

life cycle costs can be provided.

Oil-type transformers– South Boston, USA

– Pereira, Columbia

– Guarulhos, Brazil

– Bad Honnef, Germany

– Vaasa, Finland

– Vadodara, India

– Zhongshan, China

Dry-type transformers– Bland, USA

– Blumenau, Brazil

– Brilon, Germany

– Molinazzo di Monteggio, Switzerland

– Zaragoza, Spain

– Vadodara, India

– Shanghai, China

– Chonan, Korea

Manufacturing locations for converter transformers – served from your neighbourhood

1 2

3


The art of converter transformersIndividual solutions for demanding customers

Requirements for converter transformers Transformers supplying converter applications are connected

on their secondary side to a converter. The converter input

can be a passive rectifier or have an active front end using

controllable semiconductor switches. These elements create

a lot of harmonic frequencies. Different drive types are quite

diverse in the amount of harmonics produced.

Therefore, normal transformers, designed and dimensioned

for electricity distribution duty do not work satisfactorily in a

converter system. Harmonic frequencies increase the thermal,

mechanic and dielectric stresses and therefore the transformers

must be specially designed for this duty. Over-dimensioning of

a normal distribution transformer is not an adequate measure.

Transformer primary voltageThe converter transformer is usually powered by a medium or

low voltage network. Powering from a high voltage network is

also possible but not common. Only small converters can be

directly connected to a LV network without a transformer due

to harmonics and EMC requirements. Networks show different

sensitivity to harmonics and the decision whether to use an

individual supply transformer or not must be made on a case

by case basis.

Transformer secondary voltageThe input voltages for LV converters are typically between 190 V

and 900 V, and for MV drives are between 1 kV and 7 kV.

Multi-winding transformersThe rectifiers used in LV converters are usually 6- or 12-pulse

rectifiers, made of diode bridges, thyristor bridges or power

transistor solutions. The 6-pulse rectifier is supplied by a two-

winding transformer; whereas the 12-pulse rectifier needs

a three-winding transformer, having two separate secondary

windings with 30° phase shift.

MV converters and converters with higher ratings specifically

require a higher converter pulse number which is used to limit

the network harmonic distortion to an acceptable level. Pulse

numbers higher than 12 require special phase shifting, multi-

winding transformers or several transformers with phase shifts

running in parallel. Nowadays the pulse number of a converter

system can be up to 48. This requires in total eight phase-

shifted transformer windings supplying the converter system.

HarmonicsTransformers supplying converters suffer from the presence

of harmonics, whose effects differ, depending on the type of

converter. By knowing the harmonic spectrum it is possible

to carry out a complete study which will identify hot spots

that require special attention during the design of the trans-

former. The image on the next page highlights the presence

of a dispersed flux which can create hot spots at the end of

the windings and requires special attention during design.

Transformer ratings According to IEC 61378-1 rating of a converter transformer

is the same as the fundamental rating:

– Fundamental frequency rating: calculated with rated voltage

and the fundamental sinusoidal component of the load

current, 50/60 Hz) – this is used for the indication of the

guaranteed loss values and short-circuit impedance

– RMS (Root Mean Square) rating: calculated with rated

voltage and total RMS load current

– Equivalent rating: calculated with rated voltage and an

equivalent sinusoidal current which gives the same losses

in the transformer as the actual load current, including har-

monics. The equivalent current is used for temperature

rise tests.

According to IEEE C57.18.10 the rating of a rectifier trans-

former is the kVA drawn from the line. Alternative equivalent

rating parameters such as K factor can also be considered.

~~~

M Load

Electrostatic screen An earthed screen can be installed between the primary and

secondary windings. It is used to capacitively decouple primary

and secondary winding and eliminate the effects of high

frequency transients on the other winding.

CoreThe magnetic circuit is core-type with mitered joints. High-

quality grain oriented, magnetic steel is most commonly

used. Special core joints, distributed gaps and air gaps may

be used in the core construction to avoid direct current (DC)

saturation when needed.

Output transformersFor cases where converter output voltage and motor voltage

are different an output transformer is needed. These trans-

formers are two winding transformers, but are also exposed

to some increased amount of harmonics and transients from

converter switching.

StandardsThe following main standards govern converter transformers

and provide rules for correct definition of rating and specifi-

cation and for the testing of the transformers.

– IEC 61378-1 (ed. 2.0): 2011, converter transformers, Part 1,

Transformers for industrial applications

– IEC 60076 series for power transformers and

IEC 60076-11 for dry-type transformers

– IEEE Std, C57.18.10-1998, IEEE Standard Practices

and Requirements for Semiconductor Power Rectifier

Transformers

– Products complying with almost any national standard

(GB, GOST, CSA, etc.) or requiring specific certification

(e.g. UL, FM or DNV, ABS for marine applications, etc.)

can be provided

TestingRoutine tests as per standards are conducted for each

transformer unit produced. In addition, extensive type testing

programs, e.g. short circuit tests as well as temperature rise

test at equivalent rating and impulse testing among others,

can be performed for each design of the transformers.

ABB has a long experience and lots of references from

different drive applications. The high quality of our reliable

products provides an outstanding capability to withstand

short circuits. Extensive type and special testing, including

aging tests, together with our quality control, guarantee the

performance of our products.

Our compact and low-weight

transformers fully comply with

the customers’ specifi cations.

The products are developed

together with the converter

manufacturers, ensuring that

their special requirements are

always met.

M Load

Inverter

Inverter

0°

20°

20°

0°

Inverter

-20°

-20°

1 Diagram of variable speed drives | 2 Converter transformers feeding 12-pulse converter

1 Converter transformer for 36-pulse converter | 2 Simulation of magnetic field in multi-winding transformer coil

Convertertransformer

Converter Motor

1 21 2


Outstanding technical featuresHigh compatibility with different systems

ABB’s liquid-immersed transformers– Mechanical construction

Transformers for lower power range have mostly corrugated

tanks either hermetically sealed or conservator type with

flexible cooling fins. However, transformers with ratings

of approximately 7´000 kVA and above, have tanks with

detachable radiators providing adequate cooling. In order

to save space, or for some other special reason, fans can

be added to ensure more efficient cooling. Also water-

cooled heat exchangers can be used instead of radiators

– Insulating liquids

Different insulating liquids can be chosen for VSD supply

transformers.

– Mineral oil-based inhibited transformer oil for industrial

installations

– Silicone oils (non-toxic and stable, for reduced fire risk)

– Midel®, a synthetic ester-based insulating liquid (bio-

degradable and non-toxic, for reduced fire risk)

– BIOTEMP®, a renewable and biodegradable vegetable

oil, for reduced fire risk)

– Bushings and enclosures

The normal bushings used are solid porcelain bushings.

Outer cone bushings for plug-in type cable terminals are

optional.

Most of the VSD duty transformers are installed in an

industrial environment and equipped with air insulated cable

termination boxes. These can be used for either HV or LV

side, or for both. A variety of standardized cable box con-

structions are available permitting the cable entrance from

below, from above, or from the side. The normal protection

degree of a cable box is IP44. It may be higher as an option.

– Protection and monitoring of transformers

For hermetically sealed transformers used in VSD duty, the

recommended protection and monitoring devices are only

two:

– DGPT2, integrated protection device, which combines

the gas relay, over-temperature alarm, trip device and

sudden pressure relay functions.

– Pressure relief device

For the conservator transformers, the recommended

protection and monitoring devices are:

– Thermometer with alarm and trip contacts

– Oil level indicator

– Pressure relief device

– Buchholz relay

– Silicagel breather

Additionally you may select winding temperature indicators,

current transformers, surge arresters and different on-line

monitoring devices.

– Environmental classifications and surface treatment

ABB oil-filled transformers can be installed in the toughest

environmental conditions ranging from high altitudes with

cold temperatures to hot and humid conditions with high

corrosivity. Ex-proof designs for hazardous areas are also

available.

Transformers can either be painted or hot-dip galvanized

and painted. Enviromental classes are available up to

C5-M & I ISO classes. The standard color is RAL 7035,

light grey. Other shades are optional.

ABB’s dry-type transformers– Coil technologies: in order to best fi t your specifi c require-

ments we provide converter transformers with different coil

technologies:

– Vacuum cast coil (VCC): high quality, well-protected

windings

– Vacuum pressure impregnation (VPI): allowing efficient

cooling

– RESIBLOC ®: ultimate mechanical strength, qualified for

extreme climatic conditions (- 60 °C)

– Simple installation: ABB dry-type transformers allow simple

installations, can be placed close to the load, are self-extin-

guishing and contain a minimum of combustible mass.

– Enclosures and cooling: all our transformers can be provided

without or with enclosures of any protection degree (IP) or

of any NEMA type.

The enclosures can be ventilated or be equipped with an

air-to-air or an air-to-water heat exchanger for cooling

purpose. Depending on enclosures and customer require-

ments natural or forced convection is possible.

– Direct and indirect water cooling: these are transformers

and reactors where the windings are directly cooled with

water. It allows very effi cient removal of the loss heat. If the

converter uses deionized water for cooling purpose, the

same water circuit can be used for the transformer where

the windings are made with hollow conductor. If only normal

tap water is available a water-cooled heat sink is installed

into the winding.

– Winding temperature monitoring is achieved by Pt100

probes placed in the windings and connected to digital

relays. The relays can be equipped with remote reading

facilities.

– A large variety of accessories is available to optimize the

functionality of the transformers: cable boxes, measurement

or protection current transformers, on-board earthing switch,

anti-vibrators, etc.

Transformers are built to match the

requirements of any drive, from any

manufacturer.

LV-drivesSeries Drive Power Output Pulse Input transfomer voltage number

- ACS 550 General purpose up to 350 kW up to 480 V separate

- ACS 800, ACS 880 Industrial up to 5´600 kW up to 690 V 6, 12, AFE separate

MV-drivesSeries Drive Power Output Pulse Input transfomer voltage number

- ACS 1000 General purpose 315 - 5´000 kW 2.3 - 4.16 kV 12, 24 separate or integrated

- ACS 2000 General purpose 250 - 1´600 kW 4.0 - 6.9 kV AFE, 24 direct connection,

separate or integrated

- ACS 5000 General purpose 1.7 - 32 MW 6 - 6.9 kV 36 separate or integrated

- ACS 6000 Special purpose 3 - 27 MW 3 - 3.3 kV 12, 24 separate

- LCI Load-commutated inverter 2 - 72 MW 2.1 - 10 kV 6, 12, 24 separate

1 Liquid-immersed converter transformer | 2 Dry-type transformer for converter applications

1 2

Transformers and reactors are also provided for ABB‘s large family of air-cooled and water-cooled drives


Our referencesA broad variety of installations

Eskom, coal-fired power stations, South Africa– Total quantity of units:

34 transformers

– Ratings: 5.8 MVA to 11.7 MVA

RESIBLOC dry-type transformers

– Enclosure: IP54 with air-to-air heat

exchanger system

– Pulse: 12-pulse

– Special customer requirements:

refurbishment of existing equipment

in coal-fired power stations

Esperanza gold and copper mine, Chile – Total quantity of units:

12 transformers

– Ratings: 19 MVA liquid-immersed

transformers for SAG and Ball mills

supply duty together with 630 kVA

excitation transformers

– Enclosure: IP55, ONAN

– Pulse: 6- and 12-pulse


high altitude 2´300 m.a.s.l. with

extreme environmental conditions.

Special impedance design

Oasis of the SeasWorld’s largest cruise ship for 4´000

passengers.

– Total quantity of units:

8 transformers

– Ratings: 5.85 MVA to 11.7 MVA

RESIBLOC dry-type transformers

– Enclosure: IP44, AFWF

– Pulse: 24-pulse


transformer coils exchangeable

on-board; limitations for dimensions

and weight

ESPO, East Siberia Pacific Ocean pipeline, Russia– Total quantity of units:

48 transformers

– Ratings: 9´352 kVA and 4´676 kVA

liquid-immersed transformers

– Enclosure: IP66, ONAN

– Pulse: 12-pulse


Full GOST-certification, seismic de-

sign, special tank design to withstand

-60 °C transportation temperature,

well-proven drive specific transformer

technology based on long experience

and knowledge from special projects

failures

Pumping stations in various locations– Total quantity of units:

24 reactors

– Ratings: 2 x 2 mH / 3´600 A VCC

dry-type DC-link smoothing reactors

– Enclosure: IP00, WF

– Operating voltage: 5.4 kV DC


single phase, shell-core design.

The use of forced water cooling

has allowed to reduce considerably

the dimensions of this component,

which can be designed for voltages

up to 15 kV DC and more than 6 kA

Sanmen nuclear power plant, China– Total quantity of units:

2 transformers

– Ratings: 19.5 MVA, 13.8 / 1.32 kV

VCC dry-type transformers

(3 x 6.5 MVA single phase)

– Enclosure: IP21, AN

– Static Excitation System Transformer


single phase transformers, assembled

at site into three-phase configuration;

with a total of 15 CTs on primarry and

secondary windings for protection and

measuring; primary connection through

isolated phase duct

1 Transformer for Eskom´s coal-fired power stations | 2 Esperanza Gold and Copper Mine | 3 Oasis of the Seas

1 2

3

Usina de Pelotizaçao, Vitoria (ES), Brazil– Total quantity of units:

7 transformers

– Ratings: from 2.5 MVA to 10.1 MVA,

13.8 / 6 x 1.92 kV VPI dry-type trans-

formers

– Enclosure: IP54 with air-to-water heat

exchangers

– Pulse: 36-pulse, single-core


Primary windings use special conduc-

tors to cope with demanding electrical

and mechanical parameters

Refinery, South America– Total quantity of units:

1 transformer

– Ratings: 9‘040 kVA / 7‘030 kVA,

13.8 / 1.92 kV VCC dry-tpe trans-

formers

– Enclosure: IP23, AF or AN

– Pulse: 36-pulse, single-core


reduced footprint and low losses,

hi-T Plus insulation system for

longer lifetime and improved

overload performance

Three-phase iron-cored fi lter inductors for ABB ACS1000 drive– Total quantity of units:

more than 300 inductors

– Ratings: 6.8 mH, 116 A

VPI dry-type reactors

– Enclosure: IP00,

installed within the drive panel

– Operating voltage: up to 4 kV


horizontal installation,

forced air cooling and compact

overall dimensions

Contact us

ABB Ltd.Affolternstrasse 44

P.O. Box 8131

8050 Zurich, Switzerland

www.abb.com/transformers

Note:We reserve the right to make technical changes or

modify the contents of this document without prior

notice. With regard to purchase orders, the agreed

particulars shall prevail. ABB does not accept any

responsibility whatsoever for potential errors or pos-

sible lack of information in this document.

We reserve all rights in this document and in the

subject matter and illustrations contained therein.

Any reproduction, disclosure to third parties or

utilization of its contents - in whole or in parts - is

forbidden without prior written consent of ABB.

Copyright© 2013 ABB

All rights reserved

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1LDE000115 Transformers for converter applications 230413.indd

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